Field of the Invention
This invention relates to curable epoxy resins. More particularly it relates to novel curing agents.
Prior Art
Epoxy resins constitute a broad class of polymeric materials having a wide range of physical characteristics. The resins are characterized by epoxide groups which are cured by reaction with certain catalysts or curing agents to provide cured epoxy resin compositions with certain desirable properties. One such class of curing agents is, the anhydrides. Another is the carboxylic acids. It is known however that anhydrides and carboxylic acids form encapsulations which are brittle and fail when subjected to thermal cycling. Also these curing agents produce resins with poor curing qualities.
There is a need in the art for an epoxy curative that produces cured resins which display flexibility and resistance to thermal cycling superior to that found in resins cured with anhydrides and carboxylic acids.
U.S. Pat. No. 4,304,889 discusses the use of bis(hydrogen maleates) of polyoxyalkylene polyamines as an accelerator for curing a base resin with a difficult to cure aromatic polyamine.
Accelerators are compounds added in minor amounts to epoxy resin formulations to enhance the cure. They enhance the cure by reducing curing temperature, reducing curing times or driving curing to completion. Accelerators are added to the resin mixture in minor amounts and have no effect on the properties of the cured epoxy resin.